1. Field of the Invention
The present invention generally relates to a 3D display technology field, and more particularly to a 3D image system and 3D glasses.
2. Description of Prior Art
With the progressive development of 3D display technology, user requirements for the quality of 3D display are getting higher and higher.
Please refer to FIG. 1, in a conventional 3D image system, a liquid crystal display monitor comprises a monitor 11 and further comprises a ½λ wave plate 12, a ¼λ wave plate 13, and a polarizer 14. The ½λ wave plate 12 and the ¼λ wave plate 13 constitute a retarder. The ½λ wave plate 12 and the ¼λ wave plate 13 are a type of optical device, which is capable of enabling two lights perpendicular to one another to produce a phase difference during vibrations. The ½λ wave plate 12 and the ¼λ wave plate 13 are usually made of a birefringence crystal having an accurate thickness, such as quartz, calcite, or mica, and axes of the ½λ wave plate 12 and the ¼λ wave plate 13 are parallel with a surface of the wave plates.
When a linear polarized light is vertically incident into a wave plate and an angle between a vibration direction thereof and an optical axis of the wave plate is θ (θ≠0), the incident light vibrates and is separated into two components which are perpendicular to the optical axis (ordinary vibration) and parallel with the optical axis (extraordinary vibration). The two components are corresponding to an ordinary light (o light) and an extraordinary light (e light) of the wave plate. The o light and e light of the wave plate propagate along the same direction but have different speeds (refractive indices are different). An optical path difference (no-ne)d is produced after the o light and e light pass through the wave plate, wherein d is a thickness of the wave plate, and no and ne are the refractive indices of the o light and e light. A phase difference between the two perpendicular vibrations is Δj=2π(no-ne)d/λ. The two vibrations are generally synthesized to be an elliptical polarization. When Δj=2kπ (k is an integer), the two vibrations are synthesized to be a linear polarized light; when Δj=(2k+1)π/2 and θ=45 degrees, the two vibrations are synthesized to be a circular polarized light.
The ¼λ wave plate is a wave plate capable of enabling the o light and e light to produce an additional optical path difference of ¼λ. When a linear polarized light is incident into the ¼λ wave plate and θ=45 degrees, a light emitted from the wave plate is a circular polarized light. In contrast, after a circular polarized light passes through the ¼λ wave plate, the circular polarized light is converted into a linear polarized light.
The ½λ wave plate is a wave plate capable of enabling the o light and e-light to produce an additional optical path difference of ½λ. After a linear polarized light passes through the ½λ wave plate, the light is still a linear polarized light but a vibration direction thereof is required to be converted by an angle.
The lights emitted from the monitor 11 propagate along a dotted line L, and the lights emitted from the monitor 11 are converted to be linear polarized lights by the polarizer 14. After the polarized lights pass through the retarder constituted by the ¼λ wave plate 13 and the ½λ wave plate 12, circular polarized lights comprising left-circular polarized lights and right-circular polarized lights which are perpendicular to one another are formed. Then, left-eye and right-eye images are transmitted to the corresponding eyes after filtering by circular polarized 3D glasses (not shown).
Since the area of the monitor of the liquid crystal display is larger, more particularly the monitor of the large-size liquid crystal display, the large-area ¼λ wave plate 13 is required and thus the manufacturing cost and maintaining cost are higher.